593 
42 
apy 1 



Abstraction of Potassium 
During Sedimentation 



BY 
JOHN WILBUR WATSON 



A DISSERTATION 

Presented to the Faculty of the University of Virginia as a 

Part of the Requirements for the Degree of 

Doctor of Philosophy 



Abstraction of Potassium 
During Sedimentation 



BY 

JOHN WILBUR \VATSON 



A DISSERTATION 

Presented to the Faculty of the University of Virginia as a 

Part of the Requirements for the Degree of 

Doctor of Philosophy 



L\ro^ 







§ 1919 



CONTENTS 

PAGE 

Abstraction of Potassium During Sedimentation — Outline of Problem — ■ 

Previous Work by Other Investigators 5 

Important Facts Developed by Previous Workers — Nature of Absorption 6-7 

Cameron's Conclusions 7 

Experimental Work of Writer — Table 1 7-0 

Conclusions Reached by Van Bemmelen 9 

The Writer's Method of Experimentation 9-10 

Discussion of Experiments 10-11 

Negative Absorption — Table II 11-12 

Similarity of Absorption to Solution Phenomena 12 

Discussion of Conclusions Reached by Van Bemmelen and Schmidt.... 13-14 

Law Governing Absorption ! 14 

Other Evidence as to the Nature of Absorption — The Exact Nature of 

Absorption 14-15 

Discussion of Conclusions Reached by Cameron and Others — Adsorption 16-17 

Experimental Results of Writer — Table III 17-18 

Process, Cause and Character of Adsorption 18-19 

Factors Influencing Adsorption — Table IV — Time of Adsorption — Table 
V — Absorption of Acid Radical^ — -Table VI — Table VII — ^Absorption of 

Sodium and Lithium— Table VIII 19-24 

Experimental Work Indicating Adsorption of Sodittm and Lithium- — 

Table IX 24 

Salomon's Work on Absorption of Calcium— Table X — The Effects of Other 

Salts Upon Absorption 25 

Experimental Work of Writer — Table XI — Temperature Effect 25-27 

Summary 27-28 

Acknowledgment 28 

Bibliography' 29-30 



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in 2010 with funding from 
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ABSTRACTION OF POTASSIUM DURING 
SEDIMENTATION 



Outline of Problem. — Primarily this paper seeks to determine whether 
the absorption of potassium during sedimentation is chemical or physical 
in nature; secondly, to determine whether the abstraction of j)otassium 
differs in kind or degree from that of other bases; and, finally, to deter- 
mine whether the potassium is absorbed as flocculation takes place, that is 
when mudd}^ water mingles with sea water. A study of these questions 
involves, of course, minor ones which will be taken up as they are reached. 

Previous Work hy Other Investigators. — That certain salts are removed 
from solution as they percolate through soils, has been known for many 
years. Sand filters for purification of sea water and impure drinking 
water have been used since Aristotle's time; and the removal of salts 
from sea water by percolation through sand or earth filters was practiced in 
Bacon's day (l).**^ Steven Hales in 1739 found that the first portion of 
sea water passed through stone cisterns was pure (1). A list of other 
investigators who worked along the same line includes, Berzelius, Matteucie, 
Humphry Davy in 1813, Gazzeri in 1819, Lambuschini in 1830, Browner 
in 1836, Huxtable in 1848, Bernays in 1849, and Thompson and Way in 
1850. 

Berzelius filtered salt solutions through sand and found that the salt 
content was more or less removed ; Matteucie found that the concentration 
of the salt in the solution became successively smaller upon being passed 
through successive filters (1). 

Liebig found that aqueous ammonia passed through a clay filter lost 
its odor, and this result was verified by Thompson and Huxtable. Way 
in 1850 showed that soils likewise absorbed potassium, sodium, calcium, 
and magnesium, not only from solutions of their hydrates, but also their 
salts of both strong and weak acids, the acid remaining in solution 
unabsorbed and combined with other bases leached from the soil (1) ; 
phosphoric acid, however, was absorbed. Way believed this absorption of 
bases to be total (1), but Voelcker showed that this was not the case with 
ammonia, while Peters demonstrated the same to be true with potassium 
(2). Thus first crept in the idea of distribution, or the partition of a 
soluble substance between solid and liquid, by which a fraction is always 
left in solution. Many other investigators who worked on various phases 
of the problem of absorption of soluble material by soils, are mentioned 
in Bull. 52, Bureau of Soils, U. S. Dept. of Agriculture, 1908, pp. 13-26. 



aXumbers in parentheses refer to references listed at end of paper. 



ABSTKACTION OF POTASSIUM DUEING SEDIMENTATION. 



IMPORTANT FACTS DEVELOPED BY PREVIOUS WORKERS. 

The main fact developed by practically all investigators upon absorption 
which the writer wishes to emphasize, is that potassium will be absorbed 
more readily than calcium, magnesium, or sodium (3). Potassium is thus 
selectively absorbed. It is interesting to mention that ammonia and 
phosphoric acid, which, together with potassium, constitute the essential 
mineral constituents of plant food, are also selectively absorbed by soils (1). 
Ordinary soils will abstract more potassium than sodium from solutions 
in which the salts of both metals are present, even when the sodium is in 
excess (4). Potassium is removed from natural waters as they percolate 
through the soil, or else by the suspended silt carried by streams. The 
sodium is not so largely withdrawn, and hence its relative proportions 
tend steadily to increase in solution, while potassium is deposited with the 
sediments (5). 

In igneous rocks (average of all types) the proportion of sodium to 
potassium is nearly equal, whereas in river water it is in the ratio of four 
Na to one K; while in the sea it is approximately thirty to one (6). In 
sedimentary rocks the average of XaoO is 1.21 per cent, and of KgO 3.03 
per cent (7). From a study of the water in closed basins nearly the same 
proportion of sodium and potassium holds as in the case of ocean water. 
These results reveal the fact that potassium is partly removed from solution 
by the soil, partly by the agencies in rivers, and finally by agencies in the 
ocean. The greater amount seems to be removed after reaching the ocean. 
That the agencies which remove potassium in rivers and the ocean are 
mainly silt, cannot be doubted from what we know of the way soils remove 
potassium from solution. This fact will be developed later. 

According to Clarke (4), the clays and oozes of the deep sea have been 
partly leached of their alkalies; but some of the potassium from the 
original volcanic material with less sodium has been retained in the 
production of zeolites. Nearer land potassium has been used in the for- 
mation of glauconite, and still nearer, when mechanical sediments appear, 
similar discrimination is evident, namely, sodium dissolves, but potassium 
is retained. 

The bulk of the silt settles to the bottom as soon as it reaches the ocean, 
that is on mingling with a solution of electrolytes. Turbid suspensions 
of clay, kaolin, etc., in water are rapidly cleared by the addition of small 
quantities of metallic salts. The mingling of silt with sea water involves 
the same sort of phenomenon (9). It has been frequently observed that 



Cameron's conclusions. 7 

the suspended material causing the cloudiness of the water from Potomac 
River as it comes from the faucets will settle if an acid or a strong (slightly 
Iwdrolyzed) salt is added, while a hase, such as ammonia, prevents settling 
(10). The latter reference gives numerous cases of the flocculation of 
precipitates by the addition of electrolytes. This phenomenon resembles in 
a striking way the precipitation of colloids by certain electrolytes. 

Nature of Absorption. — A study of the literature on the subject of 
absorption leads to the conclusion that absorption is primarily physical, 
which is confirmed by the experimental work of the writer, although 
chemical reactions may be involved as a result. 

CAMERON'S CONCLUSIONS. 

This writer (11) states that the absorption of potassium by soils cannot 
be explained by a simple metathetical reaction. Other bases are found in 
the resulting solution, and they are not present in equivalent quantities 
to the potash; while the solution is generally acid. Similar results can be 
obtained with other absorbent media which do not contain any bases to 
replace potassium. The further fact has been established that an absorbing 
medium has a limited capacity for taking up any particular substance or 
constituent, and this capacity or saturation limit is generally independent 
of any simple molecular ratio between the absorbed substance and any 
component or constituent of the absorbing medium; organic substances 
such as dyes being absorbed in precisely the same way as mineral 
solutes (11). 

EXPEEIMENTAL WORK OF WRITER. 

Using fire-clay, kaolin, Eussian black soil, and a powdered nepheline- 
syenite, respectively, with a potassium salt solution, the writer obtained 
results which indicated that the replacement of potassium by other bases 
is not exact. In each case distilled water dissolves a certain amount of 
the bases. Even if the amount dissolved by distilled water be allowed for, 
still the replacement was not exact. 

The method of procedure of the writer in each case was to place thirty 
grams of absorbing material in contact with fifty cubic centimeters of salt 
solution (or quantities in the same ratio) for twenty-four hours, then in 
one 10 c. c. portion the alkalies were determined, and in another portion 
the remaining bases. In every case, except with kaolin, a parallel experi- 
ment was run with distilled water and the absorbent material. In the case 
of nepheline-syenite potassium and sodium only were determined. The 



8 ABSTKACTION OF POTASSIUM DUEING SEDIMENTATIOX. 

results ill each case were calculated to a ten cubic centimeter portion. 
The strength of the potassium salt solution used in each case was approxi- 
mately 1//10 normal. 

Table I.— Part 1. 



Metallic 

bases 

dissolved 

from material 


Russian black 
soil 


Fire-clay 


Kaolin 


Nepbeline-Syenite 


With 

KNO3 

solution 


With 

distilled 
water 


With 

KCl 

solution 


With 
distilled 
water 


With 

KoSO-t 
■solution 


With 
distilled 

water 


With With 
KCl 1 distilled 
solution water 


KCl (grains) 

NaCl " 

MgO " 

CaO " 

MnO " 

AI2O3 ] « 

Fe203 ( 


0.0042 
0.0032 
0.0124 
0.0004 

none 


0.0005 
0.0005 
0.0005 
0.0006 
none 

none 


0.0037 

0.0027 

0.0048 

none 

0.0045 


0.0014 
0.0011 
0.0018 
0.0039 
none 

0.0028 


0.00.32 
0.0012 
0.0006 
none 

0.0006 


13 


0.0012 
0.0223 1 0.0038 
n. d. n. d. 
n. d. n. d. 
n. d. . n. d. 

n. d. n. d. 



Table I.— Part 2. 



Potassium equivalent 
of metals, deducting 
amount dissolved by 


.0247 


.0079 


.0065 


.0124 






Potassium absorbed by 
material (see Table 
II, pp. 11 and 12).... 


.0228 


.0090 


.0044 


.0131 


Equiv. to potassium 
per cent, metals dis- 
solved from absorb- 


108.3 per cent. 


87.7 per cent. 


147.7 per cent. 


94.7 per cent. 







The Al^Og and FcoOo were weighed together and were not determined 
separatel}^ hence in calculating the K equivalent the mixture was assumed 
to be one-half AI2O3 and one-half FcoO.,. This introduces some error, yet 
for such small quantities it probably would not make an appreciable 
difference. 

Practically in every case of absorption (see table II) the solution 
after standing in contact with the soil was tested as to its acidity. Some 
were acid to litmus, yet in no case did the writer find the free acid in 
sufficient quantity to determine by titration. A fraction of a drop of 
normal base solution proved more than sufficient to make a 5 c. c. or 10 c. c. 
portion of the solution alkaline. Fire-clay with KCl solution was markedly 
acid; kaolin (high grade) ^ with KCl, KNO3, and ICSO^ solution, 
respectively, was slightly acid; kaolin (low grade) '^ with KCl solution was 



aTliese terms refer to the state of purity of the material. The high grade kaolin 
was extremely pure for a natural substance, whereas the low grade contained a large 
amount of silica as an impurity. 



CONCLUSIONS KEACHED BY VAN BEMMELEN. 9 

slight!}' acid; the limestone soil with KCl, KliOs, and KoSO^ solution, 
respectively, was slightly acid ; beanxite with KCl solution was slightly 
acid ; powdered hematite with KCl solution very slightly acid. On the 
other hand, the Eussian black soil, . powdered rutile granite, sea sand, 
calcium phosphate, limonite, precipitated calcium carbonate, fluorspar, with 
the potassium salt (carbonate of potassium excepted of course), proved in 
each case neutral to litmus. Likewise the kaolin with KCl solution and 
CaCOo was neutral. The tests with charcoal and potassium salts proved 
neutral, yet this was doubtless due to the carbonates of the alkalies present 
in the ash, as the charcoal was not purified (12). 

CONCLUSIONS UEACHED BY VAN BEMMELEN. 

The work of this investigator (13) in numerous paj^ers on absorption of 
materials from solution by colloids, indicates that absorption is not 
primarily a chemical phenomenon. He mentions the fact that it is not 
a case of substitution when absorption takes places (14). The absorptive 
power of soils is attributed by him (15) to colloidal materials mainly, such 
as colloidal silicates, iron oxide, silicic acid, and humus substances. Even 
in these cases it would be difficult to see how some of the above could 
involve a direct chemical reaction. The fact also developed by him (13), 
that colloids absorb organic as well as inorganic substances, should preclude 
the idea of its being a chemical phenomenon in general. According to 
van Bemmelen (16) if humus constituents are coagulated from aqueous 
solution by a small amount of acid or salt, they are very difficult to free 
of acids or salts by washing; hence he considers this as indicating tliat 
the acid or the salt is absorbed by a colloid. This part of his work will 
be referred to again. 

THE WEITEE'S METHOD OE EXPERIMENTATION. 

Table II, pp. 11 and 12, shows the various absorbents used, the different 
potassium salts employed, the amount of absorption in each case, the 
amount of sodium coming into solution after absorption, etc. The writer's 
method of experimentation was as follows : The proportion of absorbent 
to solution was in the ratio of thirty grams to fifty cubic centimeters of 
a N//10 solution of potassium salt. The two were shaken up together in a 
bottle with a glass stopper and left in contact usually about twenty-four 
hours, though as will be shown later this length of time was really unneces- 



10 ABSTRACTION OF POTASSIUM DUEING SEDIMENTATION. 

sary. Unless otherAvise specified the potassium salt solution was in each 
case approximately 1/^10 normal. A 5 or 10 c. c. portion was used for 
analysis, but the calculation was made always to a iO c. c. basis. The 
strength of each solution was accurately determined before absorption, 
hence the amount absorbed was found by difference. The alkalies were 
determined by the platinum chloride method of J. Lawrence Smith, 
obtaining sodium by difference; however, in several cases the platinum in 
the residue was reduced, and the sodium weighed as chloride, simply as 
a check. 

The limestone soil was labeled "limestone- white" from Worthington 
Valley, Md. ; the Russian black soil bore the label, "Tschernosern-Saratoff, 
State Dep^t, Russia"; the kaolin (high grade) came from Graniteville, 
S. C ; the decomposed granite ("calico" rock) came from near Charlottes- 
ville, Va. ; the hematite, limonite, fluorspar, calcium phosphate, and 
beauxite were all in a high state of purity for natural materials. 

BISCTJSSION OF EXPERIMENTS. 

Table II, pp. 11 and 13, indicates the large number of materials which 
show absorption, many of which would hardly contain materials to react 
chemically with the potassium salt. Again, the fact is brought out that 
absorjDtion cannot be attributed to any one material, such as hydrated 
silica, but rather the physical nature of the absorbent seems to play an 
important part, for example, whether in a state of fine subdivision or not. 
In this connection should be noted the small absorption shown by rock 
powders, while the decomposed material exhibits in general greater 
absorption. The order in which potassium is absorbed from its various 
salts, apparently depends upon the al^sorbent. With the limestone soil, 
the order was, carlwnate, nitrate, sulphate, chloride; the kaolin (high 
grade) showed greatest absorption with the chloride, though the carbonate 
was fairly close to this, then came the bicarbonate, nitrate, and sulphate, 
in the order named ; the Russian black soil exhibited greatest absorption 
from the carbonate, then in order the sulphate, nitrate, and chloride. 
With charcoal the sulphate and chloride showed practically the same 
amount of absorption. As a rule, the carbonates seem to exhibit the 
greatest absorption. Treutler (17) in studying the effect of various 
fei'tilizers upon the absorption of potassium by a soil, found that the 
greatest quantity of potassium was absorbed from the sulphate, carbonate, 
chloride, and nitrate, in the order named. But the absorption of the 
potassium from the carbonate and nitrate is more affected by other agencies 



NEGATIVE ABSORPTION. 



11 



than is the absorption from the siilphate or from the chloride, that from 
the carbonate being affected to tlie greatest extent. 

NEGATIVE ABSORPTION. 

Lamp black with both potassium chloride*^ and nitrate^ showed negative 
absorption, that is the water rather than the solute was absorbed. The 
chloride solution after standing twenty-four hours in contact with lamp 
black showed a concentration of .0748 gram KCl per 10 c. c, as against 
.0733 gram KCl per 10 c. c. originally, an increase in concentration of .0016 
gram KCl per 10 c. c. The nitrate solution after standing twenty-eight 
hours in contact, showed .1020 gram KNOg per 10 c. c, as against .1008 
gram KNOg originally, an increase in concentration of .0012 gram KISTOo 
per 10 c. c, of solution. It has been found (18) that charcoal exhibits 
negative absorption towards certain salts. Van Bemmelen (19) found 
that kaolin exhibited negative absorption towards sodium chloride. The 
phenomenon will be referred to again (see p. 17). 

Table II. 



Material used 
as absorbent 
(6 grams to 
10 c. c. sol.) 



A limestone soil. 



Kaolin (high grade). 



(burnt) . 



Used 

grams Absorption from 

of K salt 10 c. c. 

per 10 e. e. 



" (low grade) 

Silicious residue derived from 
a kaolin 



A flre-c'lay 



KOI 
0.0732 



K2SO4 
0.0883 
KNO3 
0.1073 
K2CO3 
0.0713 

iJOl 
0.0732 
K2SO4 
0.0882 
KNOs 
0.1073 
K2CO3 
0.0713 
KHCO3 
0.104 

KCl 
0.0732 

KCl 
0.0732 

KCl 
0.0732 

KCl 
0.0732 

KCl 
0.0732 

KCl 
0. 07.32 



Grams 
K salt 

KCl 
0.0147 

KCl 
0.0152 

KCl 
0.0147 
K2SO4 
0.0183 
KNOs 
0.0271 
K2CO3 
0.0355 

KCl 
0.0190 
K2SO4 
0.0097 
KNOs 
0.0119 
K2COS 
0.0167 
KHOO3 
0.0203 

KCl 
0.0118 

KCl 
0.0121 

KCl 
0.0028 

KCl 
0.0176 

KCl 
0.0171 

KCl 
0.0184 



Grams 
K 

0.0077 

0.0080 

0.0077 

0.0082 

0.0105 

0.0201 

0.0100 

0.0044 

0.0047 

0.0094 

0.0079 

0.0062 

0.0063 

0.0015 

0.0092 

0.0090 

0.0097 



Given up to 
10 e. c. by 
absorbent 



Grams 

Na salt 

NaCl 

0.0024 

NaCl 

0.0012 

NaCl 

0.0006 

Na2S04 

0.0011 

NaNOs 

0.0032 

Na2C03 

0.0005 

NaCl 

0.0O16 

Na2S04 

0.0039 

None 



NaCl 
0.0046 

NaCl 
0.0009 

NaCl 
0.0010 

NaCl 
0.0036 

NaCl 
0.00.37 

NaCl 
0.0056 



Grams 

Na 

0.0009 
0.0005 
0.0002 
0.0004 
0.0009 
0.0002 
0.0006 
0.0013 
None 



0.0018 
0.0004 
0.0004 
0.0014 
0.0015 
0.0022 



Time of 
digestion 



20 minutes 
5 hours 

24 hours 
24 hours 
24 hours 
24 hours 
24 hours 
16 hours 
16 hours 
24 hours 
24 hours 
24 hours 
24 hours 
24 hours 
10 minutes 
24 hours 

21 days 



aProportions used in this case were 1.5 grams to 10 c. c. solution. 



12 



ABSTKACTIOF OF POTASSIUM DUKING SEDIMENTATION. 



Table II (Continued). 



Material used 
as absorbent 
(6 grams to 
10 c. e. sol.) 



A fire-clay (finely powdered) . 

A fire-clay (burnt) 

Russian black soil 



Used 

grams 

of K salt 

per 10 c. c. 



(burnt). 



Decomposed granite 
("calico" rock) . . . 



A granite (fresh powdered).. 

Kragerite (a rutile granite 
from Norway) 

A rock powder (nepheline- 
syenite) 

Sea sand (washed, pow- 
dered) 

Precipitated calcium carbon- 
ate 



Native calcium phosphate . . . 
Hematite (powdered crystals) 

Limonite (powdered) 

Beauxite (powdered) 

Fluorspar (powdered) 

Charcoal-' 

Charcoal'' 

Charcoal"^ 



KCl 
0.0732 

KOI 
0.0:32 

KCl 
0.0Y32 

KCl 
0.0732 
K2SO4 
0.0883 
KNO3 
0.1008 
K2CO3 
COT-IS 

KCl 
0.0732 

KCl 
0.0732 

KCl 
0.0732 

KCl 
0.0732 

KCl 
0.0732 

KCl 
0.0732 

KCl 
0.07.32 

KOI 
0.0732 

KCl 
0.0732 

KCl 
0.0732 

KCl 
0.0732 

KCl 
0.0732 
KCl 
0.0732 
K^SO^ 
0.0883 
KCl 
0.0366 



Absorption from 
10 c. c. 



Grams 
K salt 

KCl 
0.0186 

KCl 
0.OD31 

KCl 
0.0433 

KCl 
0.0495 
K2SO4 
0.0595 
KNO3 
0.0590 
K2CO3 
0.0524 

KCl 
0.0256 

KCl 
0.0034 

KCl 
0.0015 

KCl 
0.0015 

KCl 
0.0250 

KCl 
0.0028 

KCl 
0.0042 

KCl 
0.0034 

KCl 
0.0012 

KCl 
0.0012 

KCl 
0.0075 

None 
KCl 
0.0054 
K2SO4 
0.0053 
KCl 
0.0044 



Orams 
K 

0.0098 

0.0016 

0.0227 

0.0260 

0.0267 

0.0228 

0.0297 

0.0134 

0.0018 

O.OOOS 

0.0008 

0.0131 

0.0015 

0.0022 

0.0018 

0.0006 

0.0006 

0.0039 

None 

0.0028 

0.0024 

0.0023 



Given up to 
10 c. c. by 
absorbent 



Time of 
digestion 



Orams 


Grams 




Na salt . 


Na 




NaCl 






0.0082 


0.0032 


24 hours 


NaCl 






0.0105 


0.0041 


24 hours 


NaCl 






0.0025 


0.0010 


24 hours 


NaCl 






0.0015 


0.0006 


15 days 


Na2S04 






0.0146 


0.0047 


24 hours 


NaNOa 






0.0061 


0.0024 


28 hours 


NaNOs 






0.0016 


0.0007 


24 hours 


NaCl 






0.0064 


0.0025 


24 hours 


None 


None 


24 hours 


NaCl 






0.0025 


0.0010 


24 hours 


NaCl 






0.0018 


0.0007 


24 hours 


NaCl 






0.0223 


0.0098 


24 hours 


NaCl 






0.0038 


0.0015 


24 hours 


! NaCl 






0.0126 


0.0050 


6 days 


None 


None 


40 hours 


NaCl 






0.0025 


0.0010 


24 hours 


NaCl 






0.0010 


0.0004 


24 hours 


NaCl 






0.0054 


0.0021 


24 hours 


None 


None 


24 hours 


NaCl 






0.0098 


0.0039 


16 hours 


Na2S04 






0.0076 


0.0012 


16 hours 


NaCl 






0.0027 


0.0011 


16 hours 



•'Proportions used in this case, 10 grams charcoal to 50 c. c. solution. 
"Proportions used )n this ease, 3 grams charcoal to 20 c. c. solution. 
■^Proportions used in this case, 10 grams charcoal to 50 c. c. solution 



SIMILARITY OF ABSORPTION TO SOLUTION PHENOMENA. 

Another fact which confirms absorption as being a physical phenomenon, 
is that it resembles in so many ways well-known solution phenomena, and 
there is a distribution of the substance, which is being absorbed, between 
the solid absorbing and liquid media, the resulting concentration of the 
latter depending upon the amount of the absorbed material in the 
solid (20). 



CON-CLUSIONS EEACHED BY VAN BEMMELEN AND SCHMIDT. 1-3 

DISCUSSION OF CONCLUSIONS REACHED BY VAN BEMMELEN 

AND SCHMIDT. 

In his (21) work upon the absorption of various solid materials in 
solution by colloids, among them potassium sulphate b}^ the red colloid 
of MnOa, van Bemmelen found in some cases the following formula 
to hold, 

(concentration in colloi d)" 
concentration in solution "" ^ constant. 

In general the relation, (""^^^- ^^ colloid) '^^ 

cone, m solution ~ '^ constant, 

varied according to the substances used. In a later paper (22) he finds 
that the concentration in the hydrogel (colloid) increases nearly propor- 
tional to the square root of the concentration in the solution, or 

(cone, in colloid )- 
cone, in solution 
He states further that the partition coefficient is not a constant, but 
a complex function of the concentration, and is dependent on the state of 
the colloid and the temperature. It appears from his work, however, that 
for a given absorbent and material to be absorbed, both n and K have definite 
values which are constant in that particular case. His investigations 
include the absorption of acids, alkalies, and alkali salts by hydrogels 
(colloids) of silicic acid, stannic acid, and black and red oxides of 
manganese. Only as a special case and under special conditions, did 

he find — -f- = K, which would be true if it were a case of solid solution 
and obeyed Henry's law. 

Schmidt (23) using van Bemmelen's results upon silicic acid with 
K,SO„ KKO3, KCl, H,SO„ HIvTOg, and HCl, endeavored to prove that 

Q = J^, held in general, or that absorption was a case of solid solution 

and obeyed Henry's law. But van Bemmelen (21) refuted these con- 
clusions as not holding in general, but simply a special ease which was 
true for certain concentrations, and where the power of absorption was 
feeble. Schmidt obtained other results which are of value in this con- 
nection. He found that iodine absorbed from solution by charcoal 

(C )^ 
obeyed the rule, - = K. Acetic acid absorbed by animal charcoal fol- 



14 ABSTRACTION OF POTASSIUM DURING SEDIMENTATION. 

lows the rule, ^, ,\ ^ — - = A', where iii = deeree of dissociation. Oxalic 
C\(l — m) 

(C )-^° 

acid absorbed by animal charcoal obeyed tlie rule, ^, ,, ^ — = K. 

•^ -^ Ci(l — m) 

C 
Therefore, instead of —^ = K, a case of solid solution, we have this 

relation holding for absorption in general, — ~ — = K, where n and K 

differ according to the absorbent, the material absorbed, the temperature, 
etc. This idea will be developed later, when the writer introduces his 
experimental results (see pp. 17 and 18). 

LAW GOVERNING ABSOEPTION. 

Another point to be considered is that absorption and leaching of 
potassium from soils obey similar simple laws, and that the equation is 
identical in form with the equation describing rate of solution (34). This 

dy 
law is expressed by Cameron (25) as follows,— ^^ — =^ {A — y), where 

y = the amount absorbed, x = amount of solution that has passed, and 
A = total amount which can ultimately be absorbed by that particular soil 
from that particular solution, while ^ is a characteristic constant. If the 
percolation be kept constant, and t (time) be substituted for x, we have 
simply an equation for a unimolecular reaction, whether physical or 
chemical. This latter equation seems almost identical with the result 
found by Lagergreen (26) in adsorption, namely, the rapidity with which 
adsorption takes place in a given unit of time is proportional to the 
difference between the mass finally adsorbed, and that adsorbed in time t. 
The significance of this will be evident in the next few pages. 

OTHER EVIDENCE AS TO THE NATURE OF ABSORPTION. 

There remains one other point which, it seems to the writer, affords 
evidence of absorption being a physical phenomenon. The quantity of 
soluble material absorbed by a soil has a marked influence upon the arrange- 
ment of the soil grains into aggregates. Different salts have widely 
different effects upon the soil structure, and the particular strength of soil 
solution for which the formation of soil aggregates is a maximum is not 
the same for each salt (27). Now if absorption were mere chemical 
replacement of base for base, the physical properties of soil particles ought 



OTHER EVIDENCE AS TO THE NATURE OF ABSORPTION. 15 

not to be appreciably altered. We know that it is a general chemical 
principle that one base or element can replace another in a given compound, 
and the physical properties not be altered to any extent. For example, 
in minerals, one base occurs replacing another, and yet the crystalline 
structure is identical with the mineral where such replacement has not 
occurred. 

The Exact Nature of Absorption. — One theory, which at first seemed to 
present possibilities, must be disposed of, namely, the coagulation of 
colloids by electrolytes. 

According to the latest authorities (28) irreversible colloids such as 
silicic acid, stannic acid, sulphides (As^Sg, AS2S5, CdS), iodide, and 
chloride of silver (Agl, AgCl), and metals (Au, Pt, Ag), as well as finely 
divided suspensions of clay, kaolin, quartz, carbon, etc., carry a negative 
charge in a solution of pure water; whereas metallic hydroxides (ferric, 
aluminium, chromic), and basic substances in general carry positive 
charges. Such substances in the colloidal condition carrying an electrical 
charge are readily precipitated by the addition of electrolytes (see ref. (10) 
on p. 7). Kegatively charged colloids are precipitated by the action of 
positive ions, positively charged colloids by negative ions (Hardy's rule) 
(29). The precipitating ion is carried down with the colloid. 

The idea occurred to the writer that this might have to do primarily 
with the removal of potassium from solution, but a study of the facts 
seems not to accord Avith this assumption. In the first place, it requires 
very little of a given electrolyte to produce precipitation, or rather very 
little is thus removed from solution (30). Again this process seems not 
to be selective ; a sodium salt will act in the same way and as readily as a 
potassium salt. The precipitating power of an electrolyte is a function 
of the valency of the ion, increasing strongly with the valency. (For 
univalent, bivalent, and trivalent metals the flocculating power is in the 
proportion of 1:;]0:1650) (31). This is significant when we remember 
the large amounts of magnesium and calcium salts in the sea. The degree 
of hydrolysis has no influence upon the flocculation (32). Further infor- 
mation upon this subject can be obtained by consulting Sehulze (33), who 
has made a quantitative study of the whole subject. 

That the coagulation of colloids by electrolytes accounts for the rapid 
settling or flocculation of silt and fine suspensions when river water reaches 
the ocean, is granted, but it could hardly account for the great selective 
removal of potassium over all other bases. When once the potassium is 
absorbed, then flocculation fixes the whole upon the bottom, but its 
importance is purely secondary. 



16 ABSTKACTION OF POTASSIUM DURING SEDIMENTATION. 

DISCTJSSIOH OF CONCLUSIONS REACHED BY CAMERON 
AND OTHERS. 

Adsorption. — Cameron (34) mentions that the absorption of a dissolved 
substance from solution by a soil may be accomplished in three ways. 
(1) It may be a mechanical inclusion or trapping, distinguished by the 
term imhibition, the most familiar and striking case being the absorption 
of water itself by a soil or sponge. (2) It may be a partial taking up of 
the dissolved substance to form a new compound or solid solution, as 
probably is the absorption of phosphoric acid by lime or ferric oxide. 
Obviously these two would hardly apply to a neutral potassium salt. 
(3) It may be the result of condensation or concentration of the dissolved 
substance on or about the surface of the absorbing medium, a phenomenon 
known as adsorption. This may be defined as the existence of a difference 
in concentration or density of a film adjacent to a bounding solid and the 
concentration or density of the mass of the liquid which bathes this solid. 
As an example, Cameron quotes from Patten, quartz grains adsorbing 
gentian violet. This dye can be washed off' the grains by water. 

The phenomenon adsorption seems to fit in well with the absorption of 
potassium in general, as will now be shown. Freundlich (36) found the 
empirical relation : 

y^m ^ Bc^ , where y is the mass of adsorbed substance, m that of 
the adsorbent, c the concentration of the unadsorl)ed ])ortion in solution, 
and B and p are constants. Or more simply \v(' put it in the 
form y/x^ = a constant, or (y)°/'x = a constant, where y = mass 
adsorbed, x that remaining in solution. Tliis, as we see, is the same foniuda 
as that mentioned on p. 14. W. Biltz (37) found that the adsorption of 
arsenious acid by freshly precipitated iron hydroxide could be expressed 
by the relation, y/^xf — 0.631. This important characteristic of all 
adsorption phenomena is here brought out, viz.: tlic percentage adsorbed 
of the total amount of the substance is greater the more dilute the original 
solution. But with stronger concentrations, of course, a relatively greater 
amount is adsorbed by weight (less by per cent) than witli weaker con- 
centrations. !N"ernst (38) classifies the work of van Bemmelen and 
Schmidt, which has already been discussed on pp. 13 and 14, as belonging to 
adsorption, and this is readily apparent after what has been developed in 
the writer's discussion. Another example which might be given is that of 
Bouchonnet (39), wlio found that ochre adsorbed certain dyes according 
to the above. Xernst (40) states that the adsorbent is not simply a solvent 



EXPERIMENTAL RESULTS OF WRITER, 17 

for the adsorbed material. For if that were the case, arsenious acid would 
have a molecular weight in iron hydroxide one-fifth of that which it has 
in water (partition law). In water its molecular weight is practically- 
normal; so the assumption of such a large dissociation in iron hydroxide 
is untenable. From these facts, it is evident that n and K in the 
expression Cg/ZCi „ = K, will vary according to the adsorbent used, and 
also the material to be adsorbed. Not always does 7i come out a whole 
number. In the case of picric acid between water and silk, Walker and 
Appleyard (41) found n = 2.7. 

In some cases adsorption may be negative (43), viz.: the solute is less 
concentrated around the adsorbent than in the remainder of solution. 
Lamp black with KCl and KNOg the writer found to be exam^oles ap- 
parently of the above (see p. 11 of this paper). Nernst (42) quotes from 
Lagergreen the case of sodium chloride with charcoal. Freundlich (43) 
mentions that negative adsorption is comparatively rare. 

EXPERIMENTAL RESULTS OF WRITER. 

These results, which class the absorption of a potassium salt under the 
head of adsorption, were made using different concentrations of potassium 
chloride, with Eussian black soil, limestone soil, kaolin (low grade), and fire- 
cla}', respectively. The results seem fully in accord with those of adsorption 
phenomena. The method of procedure is the same as that previously 
described on pp. 9 and 10. The time that the two were in contact was, 
in all cases, twenty-four hours. The general formula, C2/^(C!j^ = K, 
holds, where C^ = amount left in solution, CV = amount adsorbed, n and 
K are constants differing for each adsorbent. In each case a suitable value 
for n was selected, and K calculated accordingly. The results are tabulated 
on the page following (Table III). 



18 



ABSTEACTION OF POTASSIUM DUEING SEDIMENTATION. 



Table III. 



Adsorbent 



1. Russian black soil. 

3] " " " . 

4. " " " . 

1. Fire-clay 

2. " " 

i. " " 

1. Limestone soil 

2. " " 

3! " " ..... 

4. " " 

1 . Kaolin (low grade) 

2_ <> II .1 

3! 
4. 



Original 


KCl 


concen- 
tration 
of 


remaining 
in 10 


KCl in 
10 c. c. 
solution 


after ad- 


sorption 


Grams 


Grams 


0.0366 


0.0082 


0.0732 


0.0300 


0.1464 


0.0730 


0.3661 


0.2594 


0.0366 


0.0241 


0.0732 


0.0561 ' 


0.1464 


0.1198 


0.3661 


0.3312 


0.0366 


0.0262 


0.0732 


0.0585 


0.1464 


0.1240 


0.3661 


0.3370 


0.0366 


0.0291 


0.0732 


0.0611 


0.1464 


0.1298 


0.3661 


0.3406 



KCl 
adsorbed 
from 10 
c. c. of 
solution 



Grams 
0.0284 
0.0432 
0.0734 
0.1067 

0.0125 
0.0171 
0.0266 
0.0349 

0.0104 
0.0147 
0.0224 
0.0291 

0.0075 
0.0121 
0.0166 
0.0255 



n 


K 


3.10 


0.134 


3.10 


0.134 


3.10 


0.171 


3.10 


0.165 


2.65 


0.051 


2.65 


0.051 


2.65 


0.059 


2.65 


0.053 


2.35 


0.049 


2.35 


0.049 


2.35 


0.054 


2.35 


0.046 


2.00 


0.044 


2.00 


0.049 


2.00 


0.046 


2.00 


0.044 



Weight 
NaCl 

coming 

into 10 
c. c. after 

adsorp- 
tion of K 



Grams 

0.0028 

0.0024 

0.0034 

0.0048 

0.0049 
0.0039 
0.0054 
0.0O38 

None 
0.0006 
0.0032 
0.0016 

0.0019 
0.0009 
0.0O5O 
0.0016 



Time 
of ad- 
sorp- 
tion 
in 
hours 



24 



PROCESS, CAUSE, AND CHARACTER OF ABSORPTION. 

As will be seen from experimental results and references (4-1) the acid 
radical (carbonate excepted) is not adsorbed to any appreciable extent 
(44). The fact has already been brought out that the solution is often 
left acid after absorption (45). Patten and Waggaman (45) liave shown 
that a solution of potassium chloride agitated in contact Avith a soil, 
cotton, carbon black, or similar materials which do not themselves react 
with either the base or the acid, leaves the solution markedly acid. Keith 
(46) has shown that potassium salts are decomposed by soils yielding some 
free acid. The work of van Bemmelen (47) is along a similar line. These 
facts seem to indicate that adsorption promotes hydrolysis of the salts ,of 
potassium, by which the acid is left in solution and combines with any 
other basic material present, while the potassium hydroxide is adsorbed. 
Way (48) in his experiment upon the absorption of salts by sand, found 
an excess of the basic substance at the surface of the sand particles. Then, 
of course, if there are sufficient bases in solution to combine with all the 
free acid, the solution will be neutral. An analogous case is that found by 
Losev and Preundlich (49), where certain basic dyes are split in aqueous 
solution by charcoal, the base being absorbed, and the acid left in solution. 
The authors class this as a case of adsorption. 



PACTOES INFLUENCING ADSORPTION. 19 

That the acid and not free chloride (in the case of the chloride) is set 
free, seems evident from the work of Billitzer (50). He could get no 
coloration of starch iodide paper when tested under the proper conditions. 

It is probable that the hydrolysis which precedes adsorption is the 
result of chemical reaction induced by surfaces. Numerous cases are on 
record of such action (51). Or it may be a case of progressive hydrolysis 
promoted by unequal absoriDtion of base (e. g. IvOH) and acid resulting 
from hydrolysis. 

The literature throws light upon the ultimate cause of selective 
adsorption in general, and this would hold too for potassium, since it is 
an adsorption phenomenon. Energy changes are involved in adsorption 
(52). Ramsclen (53) says that if a dissolved substance increases the 
potential energy of a surface it will seek to leave this surface, while if it 
diminishes the same it will seek to concentrate upon the surface. Freund- 
lich (51) brings out this same idea, and attributes adsorption phenomena 
to changes of surface tension, and gives the law (quoted from Gibbs), 
that substances which lower the surface tension must be adsorbed, and 
vice versa. In case the surface tension between solid and liquid is lowered 
by the addition of a substance soluble in the liquid, it follows that there 
will be adsorption of the substance on the surface of the solid, for the 
potential energy Avill tend to become lower by further concentration at the 
bounding surface. This theory seems to be well substantiated. 

Adsorption is always selective in character. This is noted in the case 
of dyes (55), and the absorption of dyes is regarded as adsorption 
phenomenon (56). Cameron (57) has pointed out that organic substances 
such as dyes are absorbed in precisely the same manner as mineral solutes. 
Among the common bases, the order of absorption is found (58) to be 
thus: Potassium is absorbed more readily than sodium, magnesium more 
readily than calcium, and ammonium more readily than any of the other 
bases. 

FACTORS INFLUENCING ADSORPTION. 

The amount as well as the kind of surface acting has a great deal to 
do with adsorption (59). The greater the surface exposed the greater the 
absorption; hence, clay is a better absorbent than sand or loam (60). 
The writer found that the more finely fire-clay was powdered, the greater 
the adsorption of potassium. The ordinary coarsely powdered fire-clay, 
thirty grams per fifty cubic centimeters of solution, adsorbed in twenty-four 
hours 0.0171 gram KCl per 10 c. c. ; while if the fire-clay was previously 
ground in an agate mortar for ten or fifteen minutes, the adsorption was 
0.0186 gram KCl per 10 c. c. of solution, an increase of over 8 per cent. 



20 



ABSTRACTION" OF POTASSIUM DURING SEDIMENTATION. 



Experiments with burnt kaolin when lumpy and powdered, showed an even 
greater difference. 

There is no question but that colloidal materials exhibit much greater 
absorbing power both as to amount and variety than other materials (61). 
As mentioned before, van Bemmelen in numerous papers (13) considers 
the absorptive power of a soil as mainly due to colloidal oxides and silicates, 
and humus substances (62). Colloids absorb both organic and inorganic 
compounds. 

Now according to the present conception of colloidal materials of the 
irreversible kind (such as colloidal silicates and oxides), they are regarded 
as finely divided particles in suspension. According to Noyes (63) 
colloidal mixtures are defined as liquid (or solid) mixtures of two (or 
more) substances which are not separated from one another by the action 
of gravity however long continued, nor by filtration through paper, but 
which are so separated when the liquid is forced through animal mem- 
branes, the substance then remaining behind being designated as the 
colloid (64). AVe are concerned in this connection only with irreversible 
colloids, for the reversible kind such as gelatin are not even coagulated 
by electrolytes (unless in very large quantities) (63). Since greater the 
surface exposed greater the absorption, therefore if the exposed surface 
be indefinitely multiplied as is the case in colloidal mixtures, then the 
absorption will reach a maximum in that direction. In other words, 
colloidal suspensions being in as fine particles as can be obtained, represent 
that physical state of the absorbent best suited to bring about an abstraction 
of solutes from solution. When absorbed, coagulation follows, and the 
whole settles out. 

The colloidal material in an absorbent is not essential to absorption, 
although it does increase the latter. Eussian black soil, fire-clay, and 
kaolin (high grade), were heated to redness in a platinum dish, and kept 
at that temperature for at least thirty minutes. After cooling each was 
treated with potassium chloride solution in the proportion of thirty gi'ams 
to 50 c. c. N/^10 KCl solution and left in contact for twenty-four hours. 
Table lA^ below, the data of which will also be found in Table II, brings 
out clearly the experimental facts. 



Table IV (see also Table II), 





Russian black 
soil 


Kaolin 


rire-clay 


Grams 
10 c. 


KCl absorbed 
c. solution 


from 


Burnt 1 Unhiirnt 

.0256 i .0433 

1 


Burnt 
.0118 


Unhurnt 
.0190 


Bttrnt 
.0031 


Unhurnt 
.0171 











FACTORS INFLUENCING ADSORPTION. 



31 



These results indicate tliat lieating decreases but does not destroy the 
absorptive power, possibly because the colloidal material is coagulated into 
larger aggregations. i\-ny organic matter present with absorbent was com- 
pletely destroyed by heating, the Eussian black soil becoming a brick-red 
color. Comparing the amount of sodium passing into solution from burnt 
and unburnt material, the table indicates that much more was dissolved 
out of the burnt material, no doubt because heat would tend to break up 
the sodium minerals. 

Tifne of Adsorption. — The rapidity with which the potassium salt is 
taken up by the absorbent, when the two come in contact, is a |)oint worthy 
of notice. Table V brings out the prominent facts in this connection. 



Table A/^.— (Data taken from Table II.) 



• Time of digestion 


20 minutes 


5 hours 1 24 hours 


Weeks 


Absorbent 


Grams KCl absorbed from 


.0147 

.0024 

Per cent 
21.1 


.0152 

.0012 

Per cent 
9.9 


.0147 

.0006 

Per cen t 
5.4 




^ 


Grams NaCI dissolved from 


J- Limestone soil 


Per cent, equivalent NaCl of 
KCl 








TiTiie of digestion 

Grams KCl absorbed from 






24 hours 

.0433 

.0025 

Per cent 
7.3 


2 weeks 

.0495 

.0015 

Per cent 
3.8 


-- 


Grams NaCl dissolved from 


-Russian black soil 


Per cent, equivalent NaCl of 
KCl 








Thnc of digestion 

Grams KCl absorbed from 
10 c e. sol 


10 minutes 

.0176 

.0036 

Per cent 
25.9 




24 hoiirs 

.0171 
.0037 


3 iveelxS 

.0184 

.0056 

Per cent 
38.7 


1 


Grams NaCl dissolved from 
absorbent 


■Fire-clay 


Per cent, equivalent NaCl of 
KCl 


Per cent 
27.0 















From the above results it will be noticed that in some cases there 
seems to be a partial reabsorption of the sodium. Practically all of the 
potassium is absorbed as soon as the solution and absorbent come in contact. 
This lends strong support to the idea that the bulk of the potassium 
absorbed in the ocean is abstracted as soon as the silt, etc., reaches there. 



22 



ABSTKACTION OF POTASSIUM DURING SEDIMENTATION. 



These experiments are in accord with Nernst (65) who remarks that 
equilibrium, in the case of adsorption, is usually reached quickly and 
exactly. This fact, however, must be borne in mind, a soil is usually a 
complex adsorbent, sometimes containing both organic and inorganic 
substances, and this may lead to results not as exact as if it were a simple 
adsorbent. 

Absorption of Acid Radical. — The acid radical is not appreciably 
absorbed, except in the case of the carbonate radical. This was referred to 
on p. 18, and references are there given to the literature. The writer's 
experimental results will now 1)6 given upon the subject. Unless otherwise 
specified, the proportion of absorbent to solution was thirty grams to fifty 
cubic centimeters, and 10 c. c, drawn out after filtration of the mixture, 
were used for analysis. The chlorine was determined gravimetrieally as 
silver chloride; the sulphate gravimetrieally as barium sulphate; while 
the carbonate radical was determined by titration with a normal acid 
before and after absorption. The experimental results are included in 
Table VI: 

Table VI. 



Absorbent 


Grams acid radical 
in 10 c. c. K salt 


Grams acid 
radical ab- 
sorbed from 
10 c. c. 


Time of 


(6 grams to 10 c. e. 
solution) 


Before 
absorp- 
tion 


After 
absorp- 
tion 


digestion 




.0348 CI 
.0348 CI 
.0.506 S04 
.0506 SO4 
.0506 SO 4 
.0506 SO4 
.0304 COn" 
.0304 COs" 
.a304 COsb 
.0618 COs^ 


.0348 CI 
.0348 CI 
.0.507 SO4 
.0484 SO4 
.0482 SO4 
.0500 SO4 
.0245 COs 
.0150 COs 
.0120 COs 
.0516 COs 


None 

.0022 SO 4 
.0024 SO4 
.0006 SO4 
.0059 COs 
.0154 COs 
.0184 COs 
.0102 COs 


3 days 




12 days 




24 hours 




24 hours 




24 hours 




24 hours 




24 hours 




24 hours 




24 hours 


Kaolin (high , grade) 


24 hours 



'iln this case the proportions were 1% grams absorbent to 10 c. 
"Present in solution as KsOOs (potassium carbonate). 
^Present in solution as KHCOs (potassium acid carbonate). 



c. solution. 



From these results, we find that the chlorine radical is not appreciably 
absorbed; the SO^ radical is slightly absorbed in most cases; the CO3 
radical, unlike the others, is largely absorbed or fixed (purely a chemical 
reaction). If we compare the weight of CO3 radical fixed with the weight 
of potassium absorbed (Table II), we will find them almost equivalent, 
the carbonate running a little low however. This fixation of the carbonate 
radical seems to be due to the calcium and magnesium, which passing 
into solution react to yield the insoluble carbonates. 



FACTORS INFLUENCING ADSORPTION. 23 

The results in Table VII below serve to make this clear: 

Table VII. 



Grams metallic 
bases dissolved 
from absorbent 

by 10 c. c. 

K2CO3 sol. 


Grams K 

absorbed from 

10 e. c. 

K2CO3 sol. 


Grams metallic 

bases dissolved 

from absorbent 

by 10 c. c. 

KNO3 sol. 


Grams K 
absorbed from 
10 c. c. KNO3 

solution 


Absorbent 


.0016 CaO 
.0009 MgO 
.0007 Na 


.0297 K 


.0124 CaO 
.0032 MgO 
.0021 Na 


.0228 K 


;- Russian black soil 



The solution of potassium nitrate and potassium carbonate were 
equivalent in strength, approximately X/'IO. The time of digestion in 
each case Avas twenty-four hours. The above results indicate, that, even 
where more potassium is absorbed, very much less calcium and magnesium 
are found in solution, than where less potassium is absorbed. This 
difference in the two cases must be due to the fixation in large measure 
of the calcium and magnesium as carbonates. It might be mentioned that 
when the soil and solution were mixed and corked there was no indication 
of effervescence. 

Absorption of Sodium and Lithium. — The same kind of phenomena 
govern the absorption of sodium and lithium as that of potassium. The 
difference is one of degree and not of kind; potassium is absorbed in very 
much larger amounts. In some cases the absorption of sodium was hardly 
noticeable. Lithium seems to fall midway between the absorption of 
potassium and that of sodium. 

As in the case of potassium, a solution of sodium chloride was left 
acid after absorption by fire-clay, and neutral after absorption by Eussian 
black soil, although the amount of free acid could not be determined, so 
little was it. The lithium chloride which before absorption was slightly 
alkaline from a small excess of lithium carbonate, reacted acid after 
absorption by fire-clay. The other bases apparently pass into solution in 
a similar manner as in the case of potassium. In order to obtain com- 
parative results the solutions of sodium chloride and lithium chloride were 
made approximately of the same normality (I/IO) as that of potassium 
chloride. The same proportions of absorbent and solution were used as in 
the case of potassium, and they were in contact for the same length of 
time. The lithium chloride solution was made from lithium carbonate 
and normal hydrochloric acid, and was left slightly alkaline. Lithium 
was determined by the amyl alcohol method. Table VIII below gives 



24 



ABSTKACTION OF POTASSIUM DUKING SEDIMENTATION. 



results showing the amount of absorption of the clilorides of potassium, 
sodium, and lithium, by fire-clay and Eussian black soil, respectively : 







Table 


VIII. 










10 c. c. sol. KCl 


10 c. c. sol. NaCl 


10 c. c. sol. LiCl 


Absorbent 
(6 grams to 
10 c. c. sol.) 


Grams 

KCl 

absorbed 


Grams 

KOI 

dissolved 


Grams 

NaCl 

absorbed 

.0022 
.0168 


Grams 

KOI 

dissolved 


Grams 

LiOl 

absorbed 


Grams Grams 

NaOl KCl 

dissolved: dissolved 


Fire-clay 


.0171 


.0037 


.0032 
.0024 


.0076 
.0201 


0054 1 0016 


Eussian black soil 


.0433 


.002.5 


.0089 ' .0018 



These results indicate that proportionately lithium is absorbed more 
than sodium, and less than potassium. At the same time, these facts 
lead apparently to no connection between the degree of absorption and the 
atomic weights of the above metals. 

EXPERIMEMTAL WOEK INBICATIl^G ABSORPTION OF SODITJM 

AND LITHIUM. 

The partition of lithium and sodium chlorides between absorbent and 
solution follows apparently the laws of adsorption, as does potassium. 
That is, as the concentration of solution increases, the actual per cent 
absorbed becomes less. In the case of the Eussian black soil, only two 
concentrations were used, but these indicate the way in which the rule of 
adsorption is obeyed. Table IX below gives the results : 

Table IX. 



Adsorbent 



Eussian black soil. 



Original 


NaOl or 


concen- 


LiCl re- 


tration 


mammg 


of NaCl 


in 10 


or LiCl 


e. e. 


m grams 


after 


per 


adsorp- 


10 c. c. 


tion 



NaCl or 
LiCl ad- 
sorbed 
from 10 
c. c. of 
sol. 



rire-clay 












„ 






Eussian 


black 


soil 


<< 





NaCl 


NaCl 


0.0302 


0.0182 


NaCl 


NaCl 


0.0605 


0.0437 


NaCl 


NaCl 


0.1209 


0.0919 


LiCl 


LiCl 


0.0235 


0.0169 


LiCl 


LiCl 


0.0469 


0.0393 


LiCl 


LiCl 


0.1267 


0.1032 


LiCl 


LiCl 


0.0469 


0.0268 


LiCl 


LiCl 


0.1267 


0.0978 



NaCl 
0.0120 
NaCl 
0.0168 
NaCl 
0.0290 

Li 01 
0.0066 

LiCl 
0.0076 

LiCl 
0.0235 

LiCl 
0.0201 

LiCl 
0.0289 



1.85 
1.85 
1.85 

1.5 
1.5 
1.5 



Weight 

KCl 
found 

in 10 

c. c. 

after 
adsorp- 
tion of 
Na and 
Li 



0.105 


0.0020 


0.091 


0.0024 


0.105 


0.0030 


0.100 


0.0017 


0.065 


0.0016 


0.107 


n. d. 




0.0018 




n. d. 



Weight 
NaOl 
found 
in 10 
c. c. 
after 
adsorp- 
tion of 
Li 



0.0073 
0.0051 
n. d. 

0.0089 
n. d. 



Time 
of ad- 
sorp- 
tion in 
hours 



SALOMON S WOKK ON ABSORPTION OF CALCIUM. 



25 



SALOMON'S WORK ON ABSORPTION OF CALCIUM. 

Salomon (66) gives the absorption of calcium by various soils and soil 
constituents from several concentrations of calcium nitrate solution, to 
which was added sufficient ammonia to neutralize exactly the nitric acid 
of the calcium nitrate. His results show the same kind of phenomena as 
potassium salts. The writer has selected the two cases given below, and 
from his data has worked out n and K. The proportions he (Salomon) 
worked with were 100 grams to 200 c. c. of solution, or in that ratio. 



Table X. — (From Salomon's data.) 



Absorbent 


CaO in 

200 e. c. 

added 


CaO re- 
maining 
in 200 
c. c. of 
solution 


OaO 

absorbed 

by 100 

grams 

soil 


n 


K 


1 


Soil Irom Mockern 


0.1 
0.2 
0.4 
1.0 

0.2 
0.5 
1.0 


0.0788 
0.1580 
0.3096 
0.8120 

0.1743 
0.4306 
0.8619 


0.0212 
0.0420 
0.0904 
0.1880 

0.0257 
0.0594 
0.1381 


1 
1 
1 

1 

1 
] 


0.269 


? 




0.266 


3 


<i << i< 


0.292 


4 


U 11 11 


0.231 


1. 

9 


Kaolin from Salzmunde 


0.147 
161 


3. 


" 


O.160 



The Ejfects of Other Salts Upon Absorption. — Frank (67) found that 
the absorption of a potassium salt by a soil was lowered by sodium chloride. 
Treutler (68) in working on the effect of various fertilizers upon the 
absorption of potassium by a soil found that in general the addition of 
other mineral salts depressed the absorption of potassium, particularly the 
addition of sodium chloride. 



EXPERIMENTAL WORK OF WRITER. 

Using fire-clay and a solution of equivalent amounts of potassium and 
lithium chlorides, the writer found the absorption of potassium chloride 
very little affected, while the absorption of lithium chloride was very 
greatly depressed. Table XI, Part 1, brings out these facts in a concise 
manner. 

Table XI.— Part 1. 



Absorbent 

(6 grams to 10 

e. e. sol.) 


10 e. c. sol. KOl 
and LiCl 


10 e. e. 
sol. KCl 


10 e. c. 
sol. LiCl 




Grams 

KCl 
absorbed 


Grams 

LiOl 

absorbed 


Grams 

NaCl 

dissolved 


Grams 

KCl 

absorbed 


Grams 

NaCl 

dissolved 


Grams 

LiCl 

absorbed 


Fire-clay 


.0121 


.0027 


.0062 


.0125 


.0049 1 .0066 



26 



ABSTRACTION OF POTASSIUM DURING SEDIMENTATION. 



With a solution containing equivalents of potassium and sodium 
chlorides, using Eussian black soil as absorbent, the writer found that 
sodium chloride lowered the absorption of potassium chloride noticeably, 
but on the other hand the potassium chloride very greatly depressed the 
absorption of sodium chloride, proportionately, very much more. These 
results are shown in Table XI, Part 2. 



Table XL— Part 2. 



Absorbent 

(6 grams to 10 

c. c. sol.) 


10 e. c. sol. KCl 
and NaCl 


10 0. c. 


301. KCl 


10 c. c. sol. 
NaCl 




Grams 

KCl 

absorbed 


Grams 

NaCl 

absorbed 


Grams 

KCl 

absorbed 


Grams 

NaCl 

dissolved 


Grams 

NaCl 

absorbed 


Grams 

KCl 

dissolved 


Russian black soil 


.0257 .0067 


.0284 


n. d. 


.0120 


n. d. 



In every case, the solutions used contained the respective chlorides in 
equivalent amounts. 

The presence of calcium chloride in an equivalent amount lowers 
appreciably the absorption of potassium chloride using fire-clay as 
absorbent. On the other hand, the presence of magnesium sulphate in 
equivalent quantity increased the absorption of potassium chloride, using 
fire-clay as absorbent. The presence of calcium carbonate in excess of an 
equivalent amount to the potassium chloride raised the absorption of 
potassium chloride in the case of the limestone soil. These facts are shown 
in Table XI, Part 3. 

Table XL— Part 3. 



Absorbent 
(6 grams to 
10 c. c. sol.) 


10 c. c. sol. 
KCl + CaCl2 


10 c. c. sol. 
KCl + MgS04 


10 c. c. sol. 10 c. c. sol. 
KCl + CaCOs 1 KCl 




Grams 

KCl 

absorbed 


Grams 

NaCl 

dissolved 


Grams 

KCl 

absorbed 


Grams 

NaCl 

dissolved 


Grams 

KCl 

absorbed 


Grams 

NaCl 

dissolved 


Grams 

KOI 

absorbed 


Grams 

NaCl 

dissolved 


Fire-clay 


.0147 


.0045 


.0236 


.0044 


.0171 .0037 


Fire-clay 


.0171 1 .0037 


Limestone soil 


.018:'. 


.OflfiO 


.0147 


.0006 



In the case of kaolin (high grade) the carbonate seemed to retard the 
absorption of potassium chloride. By reference to the results in Table II, 
we would expect this difference in the two cases, because we find there 
that kaolin shows greater absorption of potassium chloride than of 
potassium carbonate, while the reverse is true with the limestone soil. 

The various effects of foreign materials upon the absorption of a given 
substance seems characteristic of adsorption. According to Bouchonnet 



SUMMAKY. 27 

(39) in studying the adsorption of dyes by ochre, acids affected the 
adsorption according to no one rule, alkalies greatly retarded adsorption, 
while sodium chloride accelerated the same. 

Temperature Ejfect. — The writer studied only one case as regards the 
effect of temperature upon absorption. Fire-clay, in contact with potassium 
chloride solution, was kept in boiling Avater for twenty minutes, cooled, 
and an analysis made upon a portion of the solution. Prom 10 c. c. 
only 0.0076 gram KCl was absorbed, 0.0044 gram NaCl passed into solu- 
tion, indicating that higher temperatures retarded absorption. Lager- 
green (69) working with dissolved salts and kaolin, animal black, and 
glass powder, found that adsorption decreases with rising temperature. 
Bouchonnet (39), in the case of dyes and ochre, found that temperature 
accelerated adsorption. Freundlich (70), studying adsorption in general, 
found the temperature effect to be slight. Evidently the effect varies as 
the kind of materials used differ. 

SUMMARY. 

The more important points developed from this investigation may be 
stated as follows : 

1. Absorption of potash from solution is primarily a physical 
phenomenon known as adsorption, which involves chemical reactions as a 
secondary matter. 

3. Adsorption seems to follow hydrolysis of the potassium salt, the 
base being adsorbed, while the acid combines with any other bases passing 
into solution. In most cases the acid radical is very little adsorbed. The 
fixation of the carbonate radical is not adsorption but a simple chemical 
reaction. 

3. The abstraction of potassium is different in degree only from that 
of sodium and lithium. 

4. All evidence points to the fact that potassium is abstracted as 
flocculation takes place. 

5. The presence of other salts affect adsorption of potash variously. 
Sodium chloride in particular lowers adsorption. On the other hand, 
potassium salts proportionately retard much more the absorption of salts 
of sodium and lithium than potassium itself is retarded by the latter two. 

6. It seems to depend upon the adsorbent as to what salt of potash 
shows the greatest adsorption. 



28 ABSTEACTION OF POTASSIUM DURING SEDIMENTATION. 

7. Else of temperature apparentlj^ retards the adsorption of potassium. 

8. There seems to exi.st no definite relation between absorption of 
the alkali metals and their atomic weights, the absorption of lithium, the 
lightest of them, falling between that of potassium and sodium. 

ACKNOWLEDGMENT. 

For suggesting this problem along witli man}^ helpful liints as to the 
proper mode of attacking it, the writer wishes to thank Drs. A. C. Spencer 
and Chase Palmer, of the U. S. Geological Survey, and Professor T. L. 
Watson, of the geological department of the University of Virginia. To 
Professors F. P. Dunnington and E. M. Bird, of the chemical department 
of the University of Virginia, the writer is deeply indebted for many 
valuable suggestions. He desires especially to thank Professor Dunnington, 
under whose kindly guidance the work was done. 

University of A'irginia, 
May, 1913. 



BIBLIOGRAPHY 

1. Patten and Waggaman, "Absorption by Soils," Bull. 52, Bureau of Soils, 

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2. Fetees, Lanchv. Vers.-Stat., ( 1860) , 2, 129. 

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6 The Data of Geochemistry, p. 127, also various analyses m same. 

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9 Whetham, "Recent Advances in Physical Science," pp. 144-5. 

lo' Bull. 30, Bureau of Soils, U. S. Dept. of Agric (1905), p. 65. 

11 Bull 32, Bureau of Soils. U. S. Dept. of Agric (1906), preface. 

12 Bull. 30, Bureau of Soils. U. S. Dept. of Agric. (1906), pp. 52-3. 

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17 Bull. 52, Bureau of Soils, U. S. Dept. of Agric, pp. 16-18; Landw. Vers.-Stat. 

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18 Bull. 52, Bureau of Soils, U. S. Dept. of Agric, p. 32. 

19. Zeit. Anorg. Chem. (1900), 23, 321. 

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26. Zeit. f. Phvs. Chem. (1900). R. 32, 174; Bijhang. t. K. Svenska Vet. Ak. 

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29 Stieglitz, Qual. Anal., Vol. I, 133; Hardy, Proc. Royal Soc (1899), 66, 110; 
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30. Whetham, "Recent Advances in Physical Science," p. 138. 

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33. Journ. Prakt. Chem. (1885), (2), 32. 390-407. 

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35. Cameron, "The Soil Solution," p. 60; Patten, Trans. Am. Electrochem. Soc 

(1906), 10, 67-74. 



30 ABSTRACTION OF POTASSIUM DURING SEDIMENTATION. 

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see also Lageegreen, Zeit. f. Phys. Chem. (1900), R. 32, 174. 

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38. Nernst, "Theoret. Chemistry," pp. 123-4. 

39. BoucHONNET, "Sur radsorption Des Matieres Colorantes Par Les Ocres," 8th 

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40. Nernst, "Theoret. Chemistry," p. 499. 

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42. Nernst, "Theoret. Chemistry." p. 124: Bijhang. till K. Sv. Vet. Akad. Handl. 

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43. Zeit. f. Phys. Chem. (1907), 57, 469. 

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45. Bull. 52, Bureau of Soils, U. S. Dept. of Agric., p. 27. 

46. Bull. 30, Bureau of Soils, U. S. Dept. of Agric, p. 38. 

47. See references mentioned in Bull. 30, Bureau of Soils, U. S. Dept. of Agric, 

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48. Bull. 30, Bureau of Soils, U. S. Dept. of Agric, p. 45 ; Jour. Roy. Agric Soc 

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50. Zeit. f. Phys. Chem. (1905), 45, 321. 

51. Bull. 30, Bureau of Soils, U. S. Dept. of Agric. pp. 61-62. numerous references 

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52. Bull. 52, Bureau of Soils, U. S. Dept. of Agric, p. 56. 

53. Zeit. f. Phys. Chem. (1904), 47, 337. 

54. Zeit. f. Phys. Chem. (1907). 57, 421, 468-469; see also Bull. 52, Bureau of 

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55. Bull. 52, Bureau of Soils, U. S. Dept. of Agric, p. 61. 

56. RoiiLAND, "The Colloidal and Crystalloidarstate of Matter." p. 24. 

57. Bull. 32, Bureau of Soils, U. S. Dept. of Agric, preface. 

58. Bull. 52, Bureau of Soils, U. S. Dept. of Agric, p. 61. 

59. Bvill. 30, Bureau of Soils, U. S. Dept. of Agric. pp. 61-2; Cameron, "The Soil 

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60. Cameron, "The Soil Solution," p. 48. 

61. The Data of Geochemistry, p. 488. 

62. Bull. 52, Bureau of Soils, U. S. Dept. of Agric. 20. 26, also references there 

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63. Notes. "Preparation and Properties of Colloidal Mixtures," .Journ. Amer. 

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64. Billitzer, "Eine Theorie der Kolloide und Suspensionem," Zeit. f. Phvs. Chem. 

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65. Nernst, "Theoretical Chemistry," p. 499. 

66. Bull. 52, Bureau of Soils, TJ. s". Dept. of Agric, pp. 14-15; Landw. Vers.-Stat. 

(1867), 9, 351. 

67. Bull. 52. Bureau of Soils. U. S. Dept. of Agric, p. 14. 

68. Bull. 52, Bureau of Soils. U. S. Dept. of Aoric, p. 18; Landw. Vers -Stat 

(1869), 12, 184; (1872), 15, 371. 

69. Zeit. f. Phys. Chem. (1900), R. 32, 174. 

70. Zeit. f. Phvs. Chen\ (1907). 57. A{:^\ 



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